The objective of this proposal is to characterize and enhance the vasoprotective effects of culture-modified mononuclear cells (CMMCs) and endothelial outgrowth cells (EOCs) in an animal model of acute vascular injury. Recent studies in chimeric animal models have demonstrated that bone marrow-derived cells participate in the cellular response to vascular injury. Circulating mononuclear cells, cultured in vitro under appropriate conditions, may assume an endothelial phenotype. Our goal is to adapt and modify these autologous cells for therapeutic purposes. CMMCs are generated by culturing peripheral blood mononuclear cells (PBMCs) towards an endothelial phenotype using defined conditions. Following 7 days in culture, the majority of early CMMCs express CD14 (the LPS receptor and a monocyte marker) although this heterogenous population also includes precursors to endothelial outgrowth cells (EOCs) and sloughed mature circulating endothelial cells (both CD14-). At later time points, these cultures consist of homogenous populations of EOCs (CD14-). Work in our laboratory has demonstrated potent vasoprotective effects of locally delivered early CMMCs and EOCs in a model of direct vascular injury. Our first working hypothesis is that autologous early CMMCs and EOCs exert vasoprotective actions in the injured vasculature in an endothelial dependent fashion. Our second working hypothesis is that genetic modification will further enhance the vasoprotective effects of EOCs. Our four specific aims are: Specific Aim 1: To compare the vasoprotective effects associated with local delivery of early CMMCs and EOCs. Specific Aim 2: To define the mechanisms responsible for the vasoprotective effects of early CMMC and EOC delivery. Specific Aim 3: To optimize transgene expression from genetically modified EOCs and to enhance their local vasoprotective actions. Specific Aim 4: To optimize systemic transgene expression from genetically modified EOCs and to determine their systemic vasoprotective potential. [unreadable] [unreadable]